fishchick

I have yet to do my 75 tank back up and fill it back up ! once i do the first question is how many bags of rocks would i need , and the second is how long do i run the fishless cycle?

haddaj04

You run a fishless cycles until ammonia and nitrites read 0 and you are showing nitrates. Bags of rock the rule is usually a pound of rock per gallon, so you would need about 75 lbs of rock or more depending on if it's a planted tank and if you have kuhli loaches.

COBettaCouple

http://www.fishlore.com/NitrogenCycle.htm - some good info on fishless cycling.. Also, you can turn the heater and aeration in the tank to maximum while cycling to help speed it along a little faster.

sirdarksol

The link that COBettaCouple gave is great. The bags of rock will depend entirely on what you're using, as well as the size of the tank. The problem with the "pounds per gallon" concept is that it doesn't take into account deep, narrow tanks or shallow, wide tanks. It also doesn't take into account substrates with different densities. A pound of medium sized river gravel takes up more space than a pound of sand or really fine gravel. In the end, if you're not going to have plants, it's entirely a personal preference thing. You don't have to have anything in the bottom, you could have a light dusting of substrate, or you could do a full inch or more.
If you're planting, you want at least two inches (most books say three) of substrate, and something other than standard gravel is good. If you're going with planted, I would suggest EcoComplete or a sand/fluorite mix.

haddaj04

good advice sirdarksol, didn't factor in the other variable, haha must be why you're a moderator and i'm just a fish bum.